/**Every DVD has a general description that is common to all copies.
 * But each Copy has attributes which help to disinguish the copies.
 */
public class Copy
{
    private String serialNumber; //Serial number is unique. (1)
    private String purchaseDate;
    private String purchasePrice;

    /** CONSTRUCTOR */
    public Copy(String serialNumber, String purchaseDate, String purchasePrice)
    {
        if(serialNumber != "null")
        {
        this.serialNumber = serialNumber;
        this.purchaseDate = purchaseDate;
        this.purchasePrice = purchasePrice;
    }
    }
    
    /** ACCESSORS */
    public String getSerialNumber()
    {
        return serialNumber;
    }
    public String getPurchaseDate()
    {
        return purchaseDate;
    }
    public String getPurchasePrice()
    {
        return purchasePrice;
    }
    
    /** MUTATORS */
    public void setSerialNumber(String serialNumber)
    {
        this.serialNumber = serialNumber;
        //(1) A check is performed. If there is already a copy with the same
        //serialNumber this change will not be applied to this instance.
        //STEFO: I will implement this stuff soon.
    }
    
    public void setPurchaseDate(String purchaseDate)
    {
        this.purchaseDate = purchaseDate;
    }
    public void setPurchasePrice(String purchasePrice)
    {
        this.purchasePrice = purchasePrice;
    }
}
